1. Field of the Invention
The present invention relates to a controller and a controlling method of an electric vehicle.
2. Description of the Related Art
Japanese Patent Unexamined Publication No. 2003-9566 (JP2003009566: equivalent of US2002190683) discloses a controller of a vehicle using an electric motor. For making a vibration damping control, this controller includes a control block having a transmission characteristic expressed by Gp(s), a subtractor for obtaining a deviation between the control block's output and a motor revolution speed, and a control block having a transmission characteristic expressed by H(s)/Gp(s). In this case, the difference between the denominator order of H(s) and the numerator order of H(s) is so set as to be more than or equal to the difference between the denominator order of Gp(s) and the numerator order of Gp(s). With this, an effect of vibration damping can be brought about even when an accelerator is stepped down from a stop state or a deceleration state.
According to the method disclosed in JP2003009566, the vehicle's torsional vibration characteristic which is to be controlled is defined as an identification model Gp(s). In this case, a torque target value and the like for determining a torque command value relative to a motor is calculated by using a filter having the transmission characteristic expressed by H(s)/Gp(s) which uses Gp(s). As such, when the vehicle's transmission characteristic is deviated from the identification model Gp(s), a vibration may occur to an output torque (feedback torque) according to a resonant characteristic of 1/Gp(s).